I'm sorry I didn't respond earlier, I was asleep when you requested help on the lore. Well, I have decided to respond. Here's what my take on the lore could be:

The Cult of Fluttershy was founded one day by a lone wanderer that roamed the world of Equestria. He was walking on his sorrowful, aimless journey through one part of a certain field in Equestria when he found a pony in the field. He had seen them before, but this one.. It had something special about her, something to.. Love about her. He wanted to approach this pony, to hug her, to embrace her. He decided against it though. More must know of this majestic beauty.

The Lone Wanderer started telling everypony near him about this wonderful pony in this field, which is sat alone, and may have certain powers. He had somewhat of an entourage in his wake, following his lead to this pony. He let the ponies approach this other pony first, so he didn't alert her.

This pony was actually well known to the other residents. The wanderer asked one pony "Who is this lovely pony I see in this field?" The pony replied back "Her name is Fluttershy. She is usually very caring, and thoughtful, but occasionally gets sorrowful when a shortage of people love her. I suggest speaking with her."

The wanderer slowed his step, making sure to be careful. When he deliberately went directly in-front of Fluttershy, she let out a little scream. It was a sign of alert, but not one of fear. He knelt down, and spoke to her, saying; "Do you feel alright? Why are you in this field alone?"

She turned around slowly, but surely meeting his eyes, locking direct contact with them. The wanderer was mesmerised. She said, in a quiet and soft voice "No one loves me, no one cares for me anymore. It's not like it used to be." The wanderer flinched slightly. He was going to have to be brutally honest here, and it could be embarrassing. He muscled up, and said "Well.. I love you."

This garnered quite a shocked response from Fluttershy. She looked at him with a sudden happiness on her face, nearly shouting "You love me! Well, I can only say this.. Yay!" Fluttershy had to draw out the yay, taking in a deep breath, and exaggerating the let out of the word. It was fantastic to see such a unique person, thought the wanderer. The two grew to be good friends, and Fluttershy even allowed a picture of the two of them together to be taken.

An idea sparked in the wanderer's mind after this. He had evidence to prove something truly lovely existed in this world, and could not allow for it to simply be ignored. Upon ending his long journey through Equestria, he decided to show people what a truly lovely person Fluttershy is. More people followed in the wanderer's wake, taking a liking to Fluttershy.

The wanderer called this.. The Cult of Fluttershy. A group few may want to be part of today, but a cult which brings true happiness to those that enter it's ranks.